112 lines
2.4 KiB
Go
112 lines
2.4 KiB
Go
// vfsgendev is a convenience tool for using vfsgen in a common development configuration.
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package main
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import (
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"bytes"
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"flag"
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"fmt"
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"go/build"
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"io"
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"io/ioutil"
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"log"
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"os"
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"os/exec"
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"path/filepath"
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)
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var (
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sourceFlag = flag.String("source", "", "Specifies the http.FileSystem variable to use as source.")
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tagFlag = flag.String("tag", "dev", "Specifies a single build tag to use for source. The output will include a negated version.")
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nFlag = flag.Bool("n", false, "Print the generated source but do not run it.")
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)
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func usage() {
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fmt.Fprintln(os.Stderr, `Usage: vfsgendev [flags] -source="import/path".VariableName`)
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flag.PrintDefaults()
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}
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func main() {
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flag.Usage = usage
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flag.Parse()
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if flag.NArg() != 0 {
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flag.Usage()
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os.Exit(2)
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}
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importPath, variableName, err := parseSourceFlag(*sourceFlag)
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if err != nil {
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fmt.Fprintln(os.Stderr, "-source flag has invalid value:", err)
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fmt.Fprintln(os.Stderr)
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flag.Usage()
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os.Exit(2)
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}
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tag, err := parseTagFlag(*tagFlag)
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if err != nil {
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fmt.Fprintln(os.Stderr, "-tag flag has invalid value:", err)
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fmt.Fprintln(os.Stderr)
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flag.Usage()
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os.Exit(2)
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}
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err = run(importPath, variableName, tag)
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if err != nil {
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log.Fatalln(err)
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}
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}
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func run(importPath, variableName, tag string) error {
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bctx := build.Default
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bctx.BuildTags = []string{tag}
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packageName, variableComment, err := lookupNameAndComment(bctx, importPath, variableName)
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if err != nil {
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return err
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}
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var buf bytes.Buffer
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err = generateTemplate.Execute(&buf, data{
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ImportPath: importPath,
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PackageName: packageName,
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BuildTags: "!" + tag,
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VariableName: variableName,
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VariableComment: variableComment,
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})
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if err != nil {
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return err
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}
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if *nFlag {
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io.Copy(os.Stdout, &buf)
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return nil
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}
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err = goRun(buf.String(), tag)
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return err
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}
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// goRun runs Go code src with build tags.
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func goRun(src string, tags string) error {
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// Create a temp folder.
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tempDir, err := ioutil.TempDir("", "vfsgendev_")
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if err != nil {
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return err
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}
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defer func() {
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err := os.RemoveAll(tempDir)
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if err != nil {
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fmt.Fprintln(os.Stderr, "warning: error removing temp dir:", err)
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}
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}()
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// Write the source code file.
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tempFile := filepath.Join(tempDir, "generate.go")
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err = ioutil.WriteFile(tempFile, []byte(src), 0600)
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if err != nil {
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return err
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}
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// Compile and run the program.
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cmd := exec.Command("go", "run", "-tags="+tags, tempFile)
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cmd.Stdout = os.Stdout
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cmd.Stderr = os.Stderr
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return cmd.Run()
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}
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